14 September 2005 Extreme adaptive optics testbed: high contrast measurements with a MEMS deformable mirror
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Abstract
"Extreme" adaptive optics systems are optimized for ultra-high contrast applications, such as ground-based extrasolar planet detection. The Extreme Adaptive Optics Testbed at UC Santa Cruz is being used to investigate and develop technologies for high-contrast imaging, especially wavefront control. We use a simple optical design to minimize wavefront error and maximize the experimentally achievable contrast. A phase shifting diffraction interferometer (PSDI) measures wavefront errors with sub-nm precision and accuracy for metrology and wavefront control. Previously, we have demonstrated RMS wavefront errors of <1.5 nm and a contrast of >107 over a substantial region using a shaped pupil without a deformable mirror. Current work includes the installation and characterization of a 1024-actuator Micro-Electro-Mechanical-Systems (MEMS) deformable mirror, manufactured by Boston Micro-Machines for active wavefront control. Using the PSDI as the wavefront sensor we have flattened the deformable mirror to <1 nm within the controllable spatial frequencies and measured a contrast in the far field of >106. Consistent flattening required testing and characterization of the individual actuator response, including the effects of dead and low-response actuators. Stability and repeatability of the MEMS devices was also tested. Ultimately this testbed will be used to test all aspects of the system architecture for an extrasolar planet-finding AO system.
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Julia W. Evans, Julia W. Evans, Katie Morzinski, Katie Morzinski, Layra Reza, Layra Reza, Scott Severson, Scott Severson, Lisa Poyneer, Lisa Poyneer, Bruce A. Macintosh, Bruce A. Macintosh, Daren Dillon, Daren Dillon, Gary Sommargren, Gary Sommargren, David Palmer, David Palmer, Don Gavel, Don Gavel, Scot Olivier, Scot Olivier, } "Extreme adaptive optics testbed: high contrast measurements with a MEMS deformable mirror", Proc. SPIE 5905, Techniques and Instrumentation for Detection of Exoplanets II, 59050Y (14 September 2005); doi: 10.1117/12.619140; https://doi.org/10.1117/12.619140
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